You have to go to Step 2 in the FILE section.
HOW TO CHANGE OR ENTER BANKING INFORMATION FOR REFUND
https://ttlc.intuit.com/turbotax-support/en-us/help-article/tax-refund/change-transferred-direct-deposit-information/L77NCbU6D_US_en_US?uid=m6tuh572
You cannot change banking information while your return is in pending, nor can you change it after the return is accepted. The IRS does not allow it.
Did you already e-file? If you did NOT e-file you can go to the FILE section step 2 to enter/change how you want to receive your refund. If you want direct deposit you need the routing number and your own account number.